Use Signal

Signal is currently the best secure messenger. It’s like WhatsApp, but its code is open source and its servers managed by a grant-funded nonprofit, which keeps no metadata. By contrast, WhatsApp is owned by Facebook, which encrypts the messages but keeps activity records/metadata. Probably it doesn’t make a difference in your life or mine which you use to ask your spouse to get milk from the store, but I want to see real privacy be the social norm so that when it matters (I’m looking at you John Podesta), it’s there. On Android it will also act as the default SMS client for insecure communication with folks that don’t have Signal installed, so you can just use it for all messaging. On iOS you can only communicate with people that have Signal installed.